Draft door guard



Feb 1942- o. w. HOLTTUM DRAFT DOOR GUARD Filed Dec. 23, 1940 Patented Feb. 10, 1942 pairs srares earner orrlce 1 Claim.

This invention relates generally to the class of stoves and furnaces and pertainsparticularly to improvements in guards or safety devices for a. furnace draft door.

In the operation of furnaces, particularly furnaces equipped with sawdust burners, there frequently occurs an explosion or combustion of fuel and gases in the ash pit, which results in the discharge of sparks from the ash pit through the draft door, and this may have serious results, particularly if the furnace is mounted upon a wooden floor or if any combustible material happens to be close to the draft door where the discharged sparks fall.

The primary object of the present invention is to provide an improved ash pit door guard or shield, which will cover the draft door which is mounted upon the ash pit door, and which will function to prevent any sparks from being discharged from the ash pit through the draft door, and which will also operate to prevent children from getting at the burning fuel in the furnace through the draft door and thus running the risk of becoming burned or causing other damage.

Another object of the invention is to provide a safety device of the character described which forms an integral part of the ash pit door and which, therefore, will move with the door, so that it will not interfere with the opening and shutting of the door when this is necessary.

Still another object is to provide a device of the character stated which, while it functions to cover the ash plt draft door to prevent the escape of sparks therefrom or to prevent children or others from tampering with the fire, is constructed so that it will not interfere with the proper flow of air into the ash pit as is necessary to maintain combustion of the fuel.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing forming part of this specification, with the understanding, however, that the invention is not confined to any strict conformity with the showing of the drawing but may be changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claim.

In the drawing:

Fig. 1 is a view in front elevation of the device embodying the invention, showing the same applied.

Fig. 2 is a vertical section on the line 2-2 of Fig. 1.

Fig. 3 is a top plan view of the applied device.

Referring now more particularly to the drawing, the numeral I generally designates a portion of the lower part of a furnace, particularly a furnace which is equipped with a sawdust burner, as it is in connection with this type of fuel handling equipment in the furnace that the present ash pit door guard or safety device is intended tobe used. The numeral 2 designates the front of the ash pit of the furnace which is closed by the usual ash pit door 3, which is hinged at one side of the open front by the hinges 4. Such ash pit doors are provided with a draft or air admitting means 5, which is controlled by a door 6 hingedly attached at its top edge, as indicated at l, to be raised or lowered by a control chain 8 which is coupled with the chimney dampers of the furnace,. not shown, in the usual well-known manner.

In carrying out the present invention, there is provided a rectangular housing of metal or other suitable non-inflammable material, which is indicated as a whole by the numeral 9. This housing has the outer or front wall ill, side walls II and top and bottom walls l2 and I 3, respectively, and it is of a height and Width to completely cover 'or enclose the ash pit door 3 in secured thereto in a suitable manner.

the manner illustrated. In other words, the height and width of the ash pit door is equal to the interior height and width of the housing at the open side thereof so that the door may be mounted in the open side of the housing and In the illustration of the invention, the housing is secured to the door 3 by means of bolts 14, which are extended through the front wall ID to and through the door 3, and which have upon their inner ends the nuts l5 which are here shown as being upon the inner side of the door and which function, when drawn up on the bolts, to draw the housing tightly into ngagement with the door or with the flange l6, which surrounds the edge of the door, as shown particularly in Fig. 2. It will, of course, be understood that the housing may be welded to the door or otherwise attached thereto and that the invention is not to be limited to the specific attaching means here shown and described.

The width or depth of the housing is suf icient to permit the draft door 6 to be swung to its fully opened position and the top I2 of the housing is provided with a chain slot l1 through which the draft door control chain may pass.

In addition to the chain slot, the top wall I2 of the housing is provided with a number of draft slots or openings [8 which are of sufficient size to provide a combined draft admission area corresponding to the area of the opening covered by the draft door.

The side wall I l of the housing is provided with suitable slots for the hinges 4, so that the housing will not interfere with the opening of the door, and as will be readily appreciated, the ash pit door may be readily opened or closed without interference from the guard housing.

As will be readily apparent from the foregoing, the present device offers a fire-proof safety means for preventing the escape of burning cinders or gases from the draft door of a furnace, and while it may be used on any furnace structure burning any kind of fuel, it is particularly suitable for and designed for use with furnaces having sawdust burners, since with this type of burner there is the greatest danger of an explosion in the ash pit with the discharge of burning gases and burning fuel therefrom through the draft door.

In a furnace equipped with a sawdust burner, there is merely employed a brick-lined burning chamber fitted into the ash pit of the furnace and a fiat grate of one piece which is raised up only high enough to permit a draft to pass underneath. This draft space is only about 1 in. in

height and must be frequently cleaned out since a small accumulation of ashes would readily choke it. Another grate rests on the first one at one end and is disposed at an inclination leading toward the fuel hopper. At times the sawdust from the hopper runs down and piles up in front of the draft door where it becomes ignited and burns, and it will thus be seen that under this condition, any explosion of gases in the ash pit would result in the expulsion of this burning fuel through the draft door, and if inflammable material were near the draft door on the outside of the furnace, it would be ignited or it might result in the burning of children or animals which might be near the furnace. With the device of the present, invention, such burning material would be caught and prevented from escaping onto the floor on which the furnace is mounted.

Another feature of the present device is that it serves to prevent children from poking sticks or other articles into the furnace ash pit as they are likely to do where an unguarded draft door is employed, particularly if attracted by the brightness of the burning fuel. The present housing shuts off any view of the draft door and due to the fact that the draft admission openings are in the top wall of the housing, it would not be possible for any article to be extended into the ash pit through the draft door and through these draft openings and to this extent also, the device functions as a safety or guard device.

What is claimed is:

The combination with a movable ash pit door having an edge provided with'an encircling laterally extending flange and an outswinging draft door, of a housing having a front wall, and side, top and bottom walls, the housing being open on the side opposite from the front wall and receiving therein the major part of the ash pit door by which the open side of the housing is closed, the side, top and bottom walls extending across the periphery of the door and bearing against said flange, said side, top and bottom walls being of substantial width whereby said draft door may freely swing outwardly into the housing for discharge of fire and ashes into the housing, the housing being secured to the ash pit door to swing therewith, and said top wall only having air admission openings therein.

OLIVER W. HOLTTUM. 

